Pond algae is something every pond owner is likely to experience at some time or another. This can be a mixed blessing as algae come with benefits and challenges. We explore the good, the bad, and the ugly of pond algae so you can better understand its impact.
Algae are a diverse group of non-flowering aquatic organisms that thrive in various water conditions. Examples include seaweeds, blanket weed (Spirogyra), duckweed, and spirulina. These organisms are found in a range of aquatic environments, such as ponds, streams, rivers, lakes, and oceans.
Unlike traditional plants, algae lack roots, stems, and leaves. They are equipped with a wider variety of photosynthetic pigments and possess unique cellular structures distinct from those of plants or animals.
Algae exist in two main forms: suspended and filamentous. Suspended algae, made up of single cells, can rapidly reproduce, often turning water a vibrant green, resembling pea soup. Filamentous algae, commonly called string algae, form threads that attach to plants, rocks, or pond walls.
Algae is mainly red or green. Red algae (Rhodophyta) are typically found in freshwater environments and derive their characteristic red hue from pigments, such as phycocyanin and phycoerythrin. Green algae, on the other hand, owe their bright green colour to chlorophyll a and chlorophyll b pigments.
It's worth noting that blue-green algae are no longer classified as algae because they are prokaryotes, whereas true algae are eukaryotic organisms.
Some of the key characteristics of algae include:
- - It can be unicellular or multicellular.
- - Found exclusively in moist or aquatic environments.
- - Reproduce via spore formation or by the fusion of haploid gametes.
- - They are free-living and photosynthetic.
- - Algae play a crucial role in aquatic ecosystems, contributing to oxygen production and forming the basis of many food chains.
Pond algae - the good
First, we’ll start with the good. In small, manageable quantities, pond algae can provide some benefits to support your pond ecosystem. The first of these is oxygen production. Sufficient oxygen in the water is vital for ensuring fish and plants can survive.
Pond algae, especially microscopic phytoplankton, photosynthesise. This releases oxygen into the water, which is vital for supporting fish and other aquatic organisms. However, this only happens during the day. Algae consumes oxygen at night.
Another good aspect of pond algae is that it forms the base of the food chain. As such, algae is a primary producer that acts as an important food source for zooplankton, small fish, and invertebrates. This makes algae, such as duckweed, important as the foundation of the aquatic food web.
In some cases, algae can also act as a natural water filter. Some algae will absorb excess nutrients found in your pond water. As such, this reduces nutrient pollution that is likely to cause issues such as uncontrollable algae blooms. This also helps maintain ecological balance.
One more good aspect of pond algae is that it can provide shelter and a habitat. Certain types of algae, like filamentous algae, provide shelter for small aquatic creatures and spawning grounds for some fish.
Pond algae - the bad
Despite the good aspects that we covered above, there are also some bad aspects of pond algae. These bad aspects can be detrimental to a healthy pond ecosystem, meaning suitable control or prevention is key.
One of the biggest problems of algae is excessive growth or blooms. This occurs when nutrient levels are too high. This can happen for several reasons, including decomposing organic matter, a build-up of fish faeces, or fertilisers flushed from the ground during rain.
When an excess of nutrients occurs, it can lead to excessive algae growth. When algae bloom uncontrollably, it blocks sunlight from reaching submerged plants. This process is known as eutrophication. This disturbs the ecosystem and heavily reduces the oxygen available in the water.
Oxygen depletion as a result of pond algae is another major problem that stems from excess algae growth. When large amounts of algae die and decompose, they consume oxygen. This leads to hypoxic conditions that can kill fish and other aquatic life.
Excessive growth of certain algae species can also result in an imbalanced ecosystem. Dominance by certain algae species can outcompete beneficial aquatic plants and reduce biodiversity. An example of this is Spirogyra. This type of algae can grow rapidly into uncontrollable blooms that result in an unbalanced ecosystem.
One other bad aspect of pond algae is that it creates slippery surfaces. Some types of algae will grow attached to the side of pond walls, rocks, or other surfaces. This can then make those surfaces slippery and unsafe for wildlife.
Pond algae - the ugly
Alongside the good and bad of pond algae, there is also the ugly. Unlike the bad elements we discussed above, the ugly aspects are far more serious to your pond’s quality and ecosystem. Here are the most ugly aspects of pond algae.
Harmful algae blooms (or HABs) can be extremely detrimental to your pond’s ecosystem. Certain algae, like cyanobacteria (blue-green algae), produce toxins that are dangerous to humans, pets, and wildlife. As such, these algae can kill fish and pond plants, destroying your pond’s ecosystem.
Excessive algae blooms can also result in an unpleasant aesthetic to your garden pond. Thick layers of algae or mats of green scum on the water’s surface make ponds look unsightly. Algae, such as filamentous algae and green pond algae, are the most notable examples that can ruin the aesthetics.
Decaying algae in a pond can also result in bad or even foul odours. Decaying algae can produce foul odours as a result of the high moisture content of the pond and the lack of oxygen available. As such, this can lead to a highly unappealing pond.
How to manage pond algae
In small, manageable quantities, certain algae types can be beneficial. As such, it’s important to understand how you can manage and control algae to ensure the maximum benefits. Here are some tips you can follow to help you manage and control algae in your pond:
- - Regularly clean out the pond to avoid excess nutrient levels. This will ensure algae blooms are less likely.
- - Add beneficial aquatic plants, such as water lilies. These can compete with algae for nutrients and sunlight, making it harder for algae to grow uncontrollably.
- - Ensure suitable aeration to maintain stable oxygen levels and discourage excessive algae growth.
- - Avoid using excessive quantities of chemicals or weed killers in your pond that can harm other life.
- - Consider opting for a blanket weed controller to help prevent uncontrollable algae blooms. These are small devices that are fitted between your filter and pump that produce a low-frequency magnetic field that is targeted to blanket weed growth mechanisms. As such, it does not affect other pond life.
Pond algae can have positive aspects, such as providing a food source or producing oxygen through photosynthesis. However, large and uncontrollable algae blooms can have significant consequences on your pond. Finding suitable methods to prevent or control excessive algae blooms is vital for ensuring your pond’s ecosystem continues to thrive.